1. Technical Field
The present invention relates generally to a semiconductor memory apparatus, and more particularly, to a page buffer control of a nonvolatile semiconductor memory apparatus.
2. Related Art
Generally, a semiconductor memory apparatus may be considered to be either a volatile memory type, such as a DRAM, an SRAM, or the like, or a nonvolatile memory type, such as an EEPROM, an FRAM, a PRAM, an MRAM, a flash memory apparatus, or the like. The volatile memory apparatus may lose stored data when power is cut off, but the nonvolatile memory apparatus may preserve stored data even after power is not supplied. Since the flash memory apparatus has advantages such as high programming speed, low power consumption, mass data storage, and the like, it has been widely used as a storage medium in a computer system or the like.
FIG. 1 is a typical configuration diagram of a NAND flash memory apparatus of the nonvolatile memory type.
The NAND flash memory apparatus in the related art includes a memory cell block 10 and a page buffer unit 20.
In the memory cell block 10, a plurality of memory cells for storing data are connected in the form of a matrix between word lines for selecting and activating the memory cells and bit lines for inputting and outputting data of the memory cells.
The page buffer unit 20 includes a plurality of page buffers PB1, PB2, etc. that are connected to the memory cells through the bit lines, and the respective page buffers PB1, PB2, etc. may provide program data to the selected memory cells or sense and store data from the selected memory cells.
A sensing output signal SAEN that is applied to the page buffer unit 20 may serve to adjust the activation timing of the page buffer unit 20 during a read operation. Here, the activation timing refers to the timing to apply values being sensed to an output node. In other words, during the read operation, the page buffer unit 20 may perform an operation of sensing the data stored in the memory cells, and may apply the sensed values to the output node at a time when the sensing output signal SAEN activated during a data sensing process is applied.
Since the sensing operation is a continuous operation, the data value read may differ depending on at which time the sensed value is captured. If the page buffer unit 20 cannot sufficiently ensure a read margin during the read operation, the page buffer unit may erroneously read the wrong data value.